1. Field of the Invention
The present invention relates to a stiffener for a vehicle body and to a vehicle body including such a stiffener. More specifically, the present invention relates to a closure member for a vehicle body which also serves to stiffen the vehicle body when the closure is in the closed position and to the vehicle body including such a closure member.
2. Description of the Related Art
Much development work has occurred in the area of vehicle bodies, and in particular automobile bodies, in the last twenty years. Development work has been performed to lighten and strengthen vehicle bodies and to improve the passenger safety provided by those bodies. At the same time, it has been desired to reduce the manufacturing costs of the vehicle bodies.
Modern vehicle bodies often exhibit improved strength compared to vehicle bodies of even ten years ago, despite the fact that the amount of material used in the body has decreased. In particular, body stiffness has increased providing improved handling of the vehicle and a reduction in body flex.
However, the front end of the vehicle body remains an area in which it is difficult for designers to achieve desired body stiffness. The need to provide access to the engine compartment for servicing and repair of the engine and the presence of suspension and/or steering mechanisms provide significant limitations within which the body designers must work.
Typically, the engine compartment on a front-engine vehicle body is box-like in design having a frame or sub frame to which the engine is mounted, a firewall/cowl extending across the back of the engine compartment, a pair of fender/side walls extending forwardly from the firewall on either side of the engine and a fascia extending between the fender/sidewalls across the front of the vehicle.
A hood, typically hinged at the firewall and latched at the fascia, is provided to enclose the top of the engine compartment and to provide the desired aerodynamic and aesthetic features to the vehicle body while allowing access to the engine compartment. The limitations on the design of the typical engine compartment (it essentially a five-sided box,) often result in vehicle bodies that are still subject, to an undesired degree, to torsional deformation and/or body flex at the engine compartment.
One prior art technique used to reduce body flex and/or to add torsional rigidity through the engine compartment has been to add bolt-on cross members in the engine compartment. For example, it is known with NASCAR and other high performance automobiles to attach bolt-on cross braces in an X-pattern, each brace extending between one side of the firewall to the opposite side of the facia and being located over the engine to stiffen the engine compartment. These braces are typically bolted on so that they can be removed, as needed, to permit engine servicing.
While such bolt-on braces can significantly improve vehicle body stiffness, they suffer from disadvantages in that they increase the difficulty in performing engine servicing (as they must be removed from the engine compartment when access is required to the engine for certain service tasks), they occupy valuable space within the engine compartment that could be used to locate other devices, they can increase the overall weight of the vehicle and they can increase the cost of manufacturing and assembling the vehicle.
Similar problems can exist, although usually to a lesser extent, with the cargo area of vehicles, such as the trunk of a passenger vehicle.